The need for replacement parts for the human body, in combination with the shortage of donor tissue and/or organs has lead to the production of replacement tissue by seeding cells onto or into a scaffold. Eventually, this should lead to tissue engineered products ready to be implanted to take over the function of missing or injured body parts.
The scaffold defines the construct shape and dimensions of the replacement to be implanted. Preferably, it is manufactured of a porous or fibrous biodegradable material, so that the degradation of the scaffold proceeds parallel with accumulation of tissue components (growth and synthesis of extracellular matrix (ECM)). Thus, the function of the scaffold, the provision of shape and strength, will gradually be taken over by the formed tissue components.
In view of the fact that cells from allogenic sources are generally rejected, autologous cells isolated from a tissue biopsy from the patient to be treated are preferably used. In order to minimize the size of the biopsy needed and to minimize the time required for cell expansion, the expanded cells have to be first applied in/onto the scaffold in an efficient manner. In addition, the cells should be distributed homogeneously throughout the scaffold, in order to enable continuous neo-tissue formation.
In general, the cells that have been harvested from the patient's body are cultured in vitro for a certain period of time, either with or without a scaffold material present. During this culturing period, proliferation and/or differentiation of the cells may take place, depending on the type of cells harvested and on the objective type of tissue.
In the literature and on the market, various cell culture media are known. These usually contain glucose, inorganic salts (minerals), amino acids, and vitamins. Other ingredients that are sometimes used include ribonucleosides, deoxyribonucleosides and antibiotics. Well-known, commercially available culture media are for instance Dulbecco's Modified Minimal Eagle's Medium (DMEM) and Alpha Minimal Eagle's Medium (α-MEM).
In the U.S. Pat. No. 5,197,985, a method is disclosed for enhancing the implantation and differentiation of marrow-derived mesenchymal cells. The method is stated to be particularly intended as a means for treating skeletal and other connective tissue disorders in humans. For the culturing of the mesenchymal cells, a medium was employed that comprised the commercially available BGJb medium (Fitton-Jackson modification) and selected lots of 10% fetal bovine serum. Further, the medium F-12 Nutrient Mixture (Ham) was used for selective marrow-derived mesenchymal cell separation.
The production of tissue engineered products will generally only commence once the type of injury or disorder is known and a specific treatment has been decided upon. While the tissue engineering is carried out, the patient is in the meantime suffering from his injuries or disorder. Thus, in order to minimize a patient's discomfort it is of great importance that the production of engineered tissues proceeds as fast as possible. A disadvantage of most of the known culture media is that they do not allow for a sufficiently fast proliferation and/or differentiation of the cells which are cultured in it. This disadvantage is particularly apparent in case human cells are cultured.